1. Field of the Invention
This invention relates to novel defoamers, i.e., defoaming or antifoaming agents, for use where foam control is desired, and more particularly, to such defoamers comprising alkylene oxide block polymers.
2. Description of Related Art
In general, polypropylene oxide adducts with glycerol and polyglycerol are known. According to German application Nos. 12 61 618; 12 80 455; and 23 60 020, and U.S. Pat. No. 3,078,236, they may be employed as defoamers in solutions of detergents and cleaning preparations. However, prior art defoamers either do not bring about the spontaneous collapse of foam, or their foam-inhibiting effect soon weakens or is lost and foam builds up again after a short period of time. Other defoamers may provide long-lasting foam inhibition, but initially inhibit the foam very slowly. Thus, it would be desirable to obtain a foam inhibitor which would inhibit foam spontaneously and also retain the property of long-lasting foam inhibition. It has now been found that an alkylene oxide block polymer of the aforementioned class of compounds provides the desired foam-inhibiting properties.